AT24RF08-EK Atmel, AT24RF08-EK Datasheet - Page 5

• Manufacturer Part Number: AT24RF08-EK
• Description: KIT EVAL FOR AT24RF08CN-10SC
• Manufacturer: Atmel
• Type: Dual Access EEPROMr

Specifications of AT24RF08-EK

• Contents: Atmel Asset ID Kit CDROM, 4 RFID Tags, Reader with Serial Port Cable and 9V Power Supply
• For Use With/related Products: AT24RF08C
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Access Protection Page
The serial port may be used to read and write the Access
Protection Page (APP) and ID Page using device access
codes of B8 and B9 (hex) instead of the normal value of A8
through AF (hex) that are used to access the rest of the
EEPROM memory. The second byte of write commands
(the word address) should be in the range of 00 through 0f
(hex) for the APP page and 10 through 1F (hex) for the ID
page. This coding is shown below.
Reads and writes to these two pages may take place on a
single byte basis only. Multi-byte operations will be
NACK’ed.
As an example, the bit encoding for a single byte read and
write command are shown below.
The AT24RF08C will acknowledge all device addresses of
B8 or B9 (hex). If the most significant three bits of the word
address are not all 0 (indicating an address outside the
Access Protection and ID pages), the chip will NACK the
access.
Bytes 0 through 7 of the APP contain 8 identical sets of
access control fields (PBx, RFx, TWx and SBx) for each of
the eight blocks of memory on the chip, which operate
according to the table listed in the Access Protection sec-
tion above. When the sticky bit in one of these bytes is set,
that byte can be written by the system. Once a sticky bit is
reset (written to zero) by the software, the byte containing it
can no longer be modified by the software until the next
power cycle. These bytes can always be read by the sys-
tem.
Byte 8 contains another PB field (PB
an additional sticky bit (SB
PB
(#9-15) of the APP and all 16 bytes of the ID page
according to the encoding listed in the “Access Protection”
section above. The value of the PB
Access Protection Page Examples
For Write Operations:
For Read Operations:
1 0 1 1 1 0 0 0
1 0 1 1 1 0 0 1
AP
bits controls read and write access to the last 7 bytes
0 0 0 A
D
7
D
6
D
AP
4
5
) as bit 7. The value of the
A
D
3
4
A
D
2
3
AP
A
D
1
) as bits 0 and 1 and
AP
2
A
D
0
1
bits can only be
D
0
D
7
D
6
D
5
D
4
D
3
changed (via writes from the serial port) when SB
This byte can always be read by the system. Bits 0 through
6 of this byte are stored in EEPROM memory and do not
change when the power is cycled or the PROT pin changes
state.
Byte 9 contains the 8 block 0 write protection bits (WP) for
each page within block 0.
Byte 10 is the tamper byte, and the LSB of this byte can be
used to determine if the “set tamper” command had been
executed from the RFID port. This bit can be reset in
software via the serial port by writing a 0 to it.
Byte 10 also contains the coil detection control. This
feature is intended to permit the system to determine if a
coil is connected to the pins. It works by driving a small
current through the coil pins and determining if there is a
low resistance between them. The coil resistance must be
less than R
enable this, the Detect Enable (DE) bit should be set to a 1.
After a delay of at least 200 µs, the Detect Coil (DC) bit is
then read and a “1” indicates that a coil is present.
Note that the RFID interface may not function properly
when the DE bit is set to a 1, and so the software should
ensure that it is always written to a 0 when the coil
detec tion sequence has completed. The DE bi t is
automatically reset to a 0 upon power-up or when PROT is
held low, but is not timed out internally by the device.
When the DE bit is low, the value of the DC bit will default
to a high state. This does not indicate the presence of a
coil, as the state of the DC bit is only valid when the DE bit
is high.
Bytes 11 through 14 are currently reserved and should not
be used by the system. Byte 14 may not be written by the
device (via either interface) at any time.
D
2
D
1
D
0
COIL
for the coil to be properly detected. To
AT24RF08C
AP
is high.
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